The present invention relates to a process for formation of breakwaters or artificial islands in a body of water.
In the offshore drilling industry, a much more complicated and expensive operation results, compared to onshore drilling. The various drilling and production facilities must withstand severe environmental conditions; high winds, various types of waves, currents and sometimes, floating ice masses. In an effort to solve these problems, the formation of artificial islands in a body of water has been proposed, with the drilling or other equipment supported on a load supportive mass.
As examples of such artificial islands, Imperial Oil Ltd. built an artificial island in Mackenzie Bay using 400,000 cubic yards of granular fill. The island was protected against erosion and ice pile-up with a large slanted slope protection area. The slope protection area was covered with a torpedo net and filter cloth. Exxon also built an artificial island in the Mackenzie Bay area in 43 feet of water. The technique involved the use of a large volume of granular fill. The edges of the island are slanted and the slopes are protected with sandbags and filter cloths. Panarctic Oils Ltd. uses an ice platform for drilling wells in the Canadian Arctic Islands area. The nearness to the North Pole allows Panarctic to form three inches of ice per day in a given area. As the thickness of the ice grows, the ice mass formed submerges. In 40-80 days, in the coldest part of the winter, the thickness of the ice mass reaches a level of buoyancy at which it can carry the entire load of drilling equipment. Drilling time is usually from January to mid-May.
Other examples of artificial island building, and land supportive masses, are disclosed in the patent literature. In U.S. Pat. No. 4,009,580, an impervious membrane is floated to a site and attached to a floating structure. The membrane is expanded by filling it with water and then sand is used to displace the water from the membrane and build an island. The contained sand is drained to remove enough water to provide external pressure on the membrane to confine the sand. Such a structure does not appear to be strong enough to withstand hostile environmental conditions such as high winds, currents and ice movements. The floatable top could be displaced from the base due to the action of waves, currents and particularly a large ice sheet. Confining pressure within an ice body can be great enough to rupture the floatable structure. If the floatable structure is designed to be strong enough, the concept reverts to a floating caisson-type structure. Any rupture of the membrane could create an unsafe condition. U.S. Pat. No. 4,103,502 teaches a similar approach where specific drainage tubes are present in the sand mass.
U.S. Pat. No. 3,798,912 teaches formation of a mobile artificial island which shows a flexible neoprene or nylon barrier.
In U.S. Pat. No. 3,842,607, a silt slurry, used for building permafrost islands of sand and gravel, is mixed with a thickenner such as sodium silicate or xanthum gum. These materials are admixed and deposited on an island being built, after sand and gravel have been piled to a satisfactory height above the surface of the water. The slurry has a silt content in the range of about 60 to 80 weight percent.
In U.S. Pat. No. 3,990,252 dredgings from the floor of a body of water are admixed with hydraulic cement and soluble alkali silicate to form an island perimeter.